use std::fs;
use std::sync::OnceLock;
use regex::Regex;
use crate::cli::Severity;
use crate::crawler::{CrawlSummary, FileKind};
use crate::reporter::{Category, Finding, Location};
use super::{Analyzer, AnalyzerError};
#[derive(Debug, Default)]
pub struct SstiAnalyzer;
impl SstiAnalyzer {
pub fn new() -> Self {
Self
}
}
impl Analyzer for SstiAnalyzer {
fn name(&self) -> &'static str {
"ssti"
}
fn analyze(&self, crawl: &CrawlSummary) -> Result<Vec<Finding>, AnalyzerError> {
let patterns = compiled_patterns()?;
let mut findings = Vec::new();
for file in &crawl.files {
if file.kind != FileKind::Source {
continue;
}
let Some(ext) = file
.path
.extension()
.and_then(|s| s.to_str())
.map(|s| s.to_ascii_lowercase())
else {
continue;
};
let contents = match fs::read_to_string(&file.path) {
Ok(c) => c,
Err(_) => continue,
};
for pattern in patterns {
if !pattern.extensions.iter().any(|e| *e == ext) {
continue;
}
for m in pattern.regex.find_iter(&contents) {
let matched = trim_match(m.as_str());
let message = format!("`{matched}` {trailer}", trailer = pattern.trailer);
let (line, column) = byte_offset_to_line_col(&contents, m.start());
let location = Location::file(file.path.clone())
.with_span(m.start(), m.len())
.with_line(line, column);
findings.push(
Finding::new(pattern.code, message, pattern.severity, Category::Security)
.with_help(pattern.help)
.with_location(location),
);
}
}
}
Ok(findings)
}
}
struct PatternSpec {
code: &'static str,
trailer: &'static str,
severity: Severity,
help: &'static str,
pattern: &'static str,
extensions: &'static [&'static str],
}
struct CompiledPattern {
code: &'static str,
trailer: &'static str,
severity: Severity,
help: &'static str,
regex: Regex,
extensions: &'static [&'static str],
}
const JS_EXTENSIONS: &[&str] = &["js", "jsx", "ts", "tsx", "mjs", "cjs"];
const PY_EXTENSIONS: &[&str] = &["py"];
const TRAILER: &str =
"compiles a template from request input — server-side template injection risk (frequently escalates to remote code execution via template-engine sandbox escape)";
const HELP_PY: &str = "never pass request input to `Template(...)`, `Environment.from_string(...)`, or `render_template_string(...)`; render a static template file with `render_template('name.html', value=user_input)` so the user value lands inside an auto-escaped slot, not in the template source itself";
const HELP_JS: &str = "never pass request input as the template source to `pug.render` / `pug.compile` / `handlebars.compile` / `ejs.render` / `nunjucks.renderString`; load templates from disk by name and pass user input as data, not as the template body";
const PATTERN_SPECS: &[PatternSpec] = &[
PatternSpec {
code: "RSTR-SSTI-001",
trailer: TRAILER,
severity: Severity::High,
help: HELP_PY,
pattern: r"\b(?:jinja2\.)?Template\s*\(\s*request\.(?:args|form|values|cookies|headers|GET|POST)(?:\.[A-Za-z_][A-Za-z0-9_]*)*(?:\[[^\]]+\]|\.get\s*\([^)]+\))\s*\)",
extensions: PY_EXTENSIONS,
},
PatternSpec {
code: "RSTR-SSTI-001",
trailer: TRAILER,
severity: Severity::High,
help: HELP_PY,
pattern: r"\brender_template_string\s*\(\s*request\.(?:args|form|values|cookies|headers|GET|POST)(?:\.[A-Za-z_][A-Za-z0-9_]*)*(?:\[[^\]]+\]|\.get\s*\([^)]+\))",
extensions: PY_EXTENSIONS,
},
PatternSpec {
code: "RSTR-SSTI-001",
trailer: TRAILER,
severity: Severity::High,
help: HELP_PY,
pattern: r"\b[A-Za-z_][A-Za-z0-9_]*\.from_string\s*\(\s*request\.(?:args|form|values|cookies|headers|GET|POST)(?:\.[A-Za-z_][A-Za-z0-9_]*)*(?:\[[^\]]+\]|\.get\s*\([^)]+\))",
extensions: PY_EXTENSIONS,
},
PatternSpec {
code: "RSTR-SSTI-002",
trailer: TRAILER,
severity: Severity::High,
help: HELP_JS,
pattern: r"\b(?:pug|handlebars|Handlebars|ejs|nunjucks|Mustache|mustache)\.(?:render|compile|renderString)\s*\(\s*req\.(?:body|query|params|cookies|headers)(?:\.[A-Za-z_][A-Za-z0-9_]*)+\s*[,)]",
extensions: JS_EXTENSIONS,
},
];
static PATTERNS: OnceLock<Result<Vec<CompiledPattern>, regex::Error>> = OnceLock::new();
fn compiled_patterns() -> Result<&'static [CompiledPattern], AnalyzerError> {
let cached = PATTERNS.get_or_init(|| {
PATTERN_SPECS
.iter()
.map(|spec| {
Regex::new(spec.pattern).map(|regex| CompiledPattern {
code: spec.code,
trailer: spec.trailer,
severity: spec.severity,
help: spec.help,
regex,
extensions: spec.extensions,
})
})
.collect::<Result<Vec<_>, _>>()
});
match cached {
Ok(v) => Ok(v.as_slice()),
Err(e) => Err(AnalyzerError::Failed {
name: "ssti",
message: format!("failed to compile a builtin ssti pattern: {e}"),
}),
}
}
fn trim_match(raw: &str) -> String {
let trimmed = raw.trim_end_matches([',', ' ', '\t']);
let trimmed = if let Some(stripped) = trimmed.strip_suffix(')') {
stripped
} else {
trimmed
};
let mut out = trimmed.to_string();
let open = out.matches('(').count();
let close = out.matches(')').count();
for _ in 0..open.saturating_sub(close) {
out.push(')');
}
out
}
fn byte_offset_to_line_col(text: &str, offset: usize) -> (usize, usize) {
let mut line = 1usize;
let mut col = 1usize;
for (i, ch) in text.char_indices() {
if i >= offset {
break;
}
if ch == '\n' {
line += 1;
col = 1;
} else {
col += 1;
}
}
(line, col)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::crawler::{CrawlSummary, DiscoveredFile, FileKind};
use std::io::Write;
use std::path::PathBuf;
use std::sync::atomic::{AtomicU64, Ordering};
static COUNTER: AtomicU64 = AtomicU64::new(0);
fn tempdir() -> Option<PathBuf> {
let n = COUNTER.fetch_add(1, Ordering::Relaxed);
let dir =
std::env::temp_dir().join(format!("rastray-ssti-test-{}-{}", std::process::id(), n));
let _ = std::fs::remove_dir_all(&dir);
match std::fs::create_dir_all(&dir) {
Ok(()) => Some(dir),
Err(_) => None,
}
}
fn run_on(name: &str, body: &str) -> Vec<Finding> {
let Some(dir) = tempdir() else {
return Vec::new();
};
let path = dir.join(name);
if let Ok(mut f) = std::fs::File::create(&path) {
let _ = f.write_all(body.as_bytes());
}
let crawl = CrawlSummary {
files: vec![DiscoveredFile {
path: path.clone(),
kind: FileKind::Source,
size: Some(body.len() as u64),
}],
skipped: 0,
errors: vec![],
};
let result = SstiAnalyzer::new().analyze(&crawl).unwrap_or_default();
let _ = std::fs::remove_dir_all(&dir);
result
}
#[test]
fn compiled_patterns_compile_cleanly() {
assert!(compiled_patterns().is_ok());
}
#[test]
fn jinja2_template_with_request_args_get_is_flagged() {
let body = "from jinja2 import Template\n@app.route('/x')\ndef x():\n return Template(request.args.get('name')).render()";
let findings = run_on("a.py", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-001"));
}
#[test]
fn render_template_string_with_request_form_is_flagged() {
let body = "from flask import request, render_template_string\n@app.route('/x', methods=['POST'])\ndef x():\n return render_template_string(request.form['template'])";
let findings = run_on("a.py", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-001"));
}
#[test]
fn jinja_environment_from_string_is_flagged() {
let body = "env = jinja2.Environment()\nt = env.from_string(request.args.get('t'))";
let findings = run_on("a.py", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-001"));
}
#[test]
fn pug_render_with_req_body_is_flagged() {
let body = "app.post('/r', (req, res) => { res.send(pug.render(req.body.tpl)); });";
let findings = run_on("a.js", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-002"));
}
#[test]
fn handlebars_compile_with_req_query_is_flagged() {
let body = "const tpl = Handlebars.compile(req.query.src);";
let findings = run_on("a.js", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-002"));
}
#[test]
fn ejs_render_with_req_body_is_flagged() {
let body = "const html = ejs.render(req.body.template, data);";
let findings = run_on("a.js", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-002"));
}
#[test]
fn nunjucks_renderstring_with_req_params_is_flagged() {
let body = "const out = nunjucks.renderString(req.params.t, {});";
let findings = run_on("a.js", body);
assert!(findings.iter().any(|f| f.code == "RSTR-SSTI-002"));
}
#[test]
fn static_template_file_render_is_not_flagged() {
let body = "from flask import render_template\n@app.route('/x')\ndef x():\n return render_template('home.html', name=request.args.get('name'))";
let findings = run_on("a.py", body);
assert!(
findings.is_empty(),
"render_template (not render_template_string) should not flag: {findings:?}"
);
}
#[test]
fn literal_template_string_is_not_flagged() {
let body = "const tpl = Handlebars.compile('<h1>{{name}}</h1>');";
let findings = run_on("a.js", body);
assert!(
findings.is_empty(),
"literal template source should not flag: {findings:?}"
);
}
#[test]
fn pug_render_with_named_file_path_is_not_flagged() {
let body = "const html = pug.renderFile('views/home.pug', { name: req.body.name });";
let findings = run_on("a.js", body);
assert!(
findings.is_empty(),
"renderFile passes data through, not template source: {findings:?}"
);
}
#[test]
fn intermediate_variable_is_not_flagged() {
let body = "const src = req.body.tpl; const html = pug.render(src);";
let findings = run_on("a.js", body);
assert!(
findings.is_empty(),
"indirect flow is taint analysis territory, not regex: {findings:?}"
);
}
#[test]
fn non_py_extension_is_skipped_for_py_pattern() {
let body = "Template(request.args.get('t'))";
let findings = run_on("a.txt", body);
assert!(findings.is_empty(), "txt should be ignored: {findings:?}");
}
#[test]
fn messages_for_same_rule_differ_by_captured_call_site() {
let body = "pug.render(req.body.tpl);\nHandlebars.compile(req.query.src);";
let findings = run_on("a.js", body);
let msgs: Vec<&str> = findings.iter().map(|f| f.message.as_str()).collect();
assert!(msgs.iter().any(|m| m.contains("pug.render(req.body.tpl)")));
assert!(msgs
.iter()
.any(|m| m.contains("Handlebars.compile(req.query.src)")));
let unique: std::collections::HashSet<&str> = msgs.iter().copied().collect();
assert_eq!(
unique.len(),
msgs.len(),
"each finding should have a distinct message: {msgs:?}"
);
}
#[test]
fn help_text_includes_remediation_idiom_for_language() {
let py_findings = run_on(
"a.py",
"from jinja2 import Template\nt = Template(request.args.get('t'))",
);
let py_help = py_findings
.iter()
.find(|f| f.code == "RSTR-SSTI-001")
.and_then(|f| f.help.as_deref())
.unwrap_or_default();
assert!(py_help.contains("render_template") || py_help.contains("auto-escaped"));
let js_findings = run_on("a.js", "pug.render(req.body.tpl);");
let js_help = js_findings
.iter()
.find(|f| f.code == "RSTR-SSTI-002")
.and_then(|f| f.help.as_deref())
.unwrap_or_default();
assert!(js_help.contains("templates from disk") || js_help.contains("template body"));
}
#[test]
fn trim_match_balances_parens() {
let raw = "pug.render(req.body.tpl,";
let out = trim_match(raw);
assert_eq!(out, "pug.render(req.body.tpl)");
}
}